Insulation lining for conduits



Feb. 13, 1945.

A. L. BAKER INSULATION LINING FOR CONDUITS 2 Sheets-Sheet 1 Original Filed May 3, 1940 t: t, L

IN VEN TOR. ABE/PTLEAKE/P Feb. 13, 1945. A. L. BAKER 2,369,204

I NSULATION LINING FOR CONDUITS Original Filed May 3, 1940 2 Sheets Sheet 2 final/ll. A 1/ 7 2 INVEjV TOR.

Patented Feb. 13, 1945 INSULATION LINING FOR CONDUITS Albert L. Baker, Summit, N. 1., assignor to The M. W. Kellogg Company, New York, N. Y., a corporation of Delaware Original application May a, 1940, Serial No. r 333,093. Divided and this application April 29, 1942, Serial No. 440,922

4 Claims.

This invention relates in general to conduits, vessels and the like, through which fluids are conducted or in which fluids are processed and in particular to novel apparatus for controlling the transfer of heat from the fluid within the conduit or vessel to the atmosphere or other external medium. This application is a division of application Serial No. 333,093, filed May 3, 1940.

It is now quite usual in many arts, such as the power plant, chemical, petroleum refining, and similar arts, to provide conduits and vessels for handling materials in the gas, or vapor, phase at extremely high temperatures and generally also under the extreme p essures. Temperatures of 1000 F., and more, and pressures of 1000 lbs.

per square inch, and more, are not uncommon.

The materials handled, furthermore, are often of a corrosive nature.

The fabricators of the conduits and vessels for this class of service have found that carbon steel, primarily because of its low creep-strength and inferior corrosion resistance at the operating temperatures, is not the best material for the purpose and have turned to alloys of superior high temperature creep-strength and corrosion resistance. These alloys aside from the special properties, just mentioned, are generally not as desirable as carbon steel as they are much more expensive, are more difllcult to fabricate, require expensive heat treatment to bring out their special properties and are more dlfllcult to maintain and repair.

Because of the extreme service temperatures it is usual to insulate conduits and vessels of this type by covering their outside surfaces with suitable insulating materials. The cost of insulating in this manner is relatively high.

I have found, when handling materials that are made up of condensable constituents in thegas, or vapor phase, or include both condensable and non-condensable constituents in the gas, or vapor, phase, that by the proper 'control of the transfer of heat from the high temperature material within the conduit, or vessel, to the metal walls, the metal of the walls can easily be kept within the temperatures range wherein carbon steel has satisfactory characteristics such as creep-strength so that by employing this mode of heat transfer control the special properties of the costly alloys are not required and the conduits and vessels can safely be made of carbon steel. I have also found that, with the materials above mentioned, by the proper control of the heat transfer the heat losses are substantially reduced and minimized.- I have further found vide a novel insulation liner adapted to line the inside surface of the walls of conduits, or vessels, which is of cheap and simple construction, may be easily and cheaply applied and makes full use of the insulation value of the insulating material employed.

It is also a primary object of the invention to provide a novel insulation liner adapted to be positioned. against the inside surfaces of the walls of conduits, or vessels, which includes an inner metal wall, that may be of non-corrosive metal, in contact with the bulk of the materials handled in the conduit, or vessel, the metal wall being such that it allows pressure equalization across the full cross-section of the conduit, or vessel, including the portion thereofoccupied by the linin and relative movement between the comdled whereby when media at high temperature are handled the expansion and thermal stresses in the conduit, or vessel, walls are materially reduced and the vessels, or conduits, may be safely fabricated from ordinary materials and designed for operation within well known limits of. temperature and pressure.

It is also an important object of this .inventio to provide a novel insulation liner adapted to be positioned against the inside surfaces of the walls of conduits, or'vessels, which is'made up of a plurality of connected sections, each of the'sections, however, being capable of limited independent movement, each section including an inner and an outer jacket between which is positioned the insulat n material, each of the jackets having at their ends corrugations, or equivalent stiffening elements, which serve to stiffen the jackets, act as stops for limiting the movement of the sections and serve to hold the insulatin material in position; the jackets being provided with passageways therein for pressure equalization.

The further objects and advantages of the invention will be readily appreciated from a consideration of the tollowingdetailed description of portion of a pipe thatincludes a connector.

I The novel apparatus of the invention is of general application and may be applied to vessels of any sort that are used for any purpose. Thus, the novel apparatus may'be used in handling liquids, solids, gases, or vapors, or mixtures thereof. When the material handled is in the gas, or vapor, phase it may be all condensable, or it may be all non-condensable, or it may include both condensable and non-oondensable' constituents.

While the invention is applicable to vessels and conduits in general, it will be disclosed in connection with a pipe.

Thus, in Fig. 1 is shown a pipe III that includes a wall with flanges I2 at its ends. Pipe in may be of any suitable material but usually carbon steel will be satisfactory. When the materials handled are sufliciently' corrosive the inside surface of pipe 10 may be defined by a suitable corrosion resistant material such as chrome steel alloy, pure nickel etc.

Within pipe I is an insulating liner ll. Liner I4 is made up. of a plurality of sections each of which includes a pair of metal jackets, l5 and I6 separated by packed fibrous insulating material i1 and I8. Jackets 15 and I; may be made of any preferred metal suited for the intended service thus, both jackets may be of carbon steel or both of alloy stee1 of special property. In high temperature service it is at present preferred to makeouter jacket l5 of light gage carbon steel and inner jacket 16 of a light gage corrosion resistant alloy such as 14% chrome steel. The thickness of jackets l5 and i6 has been exaglong flber plugs it serve to prevent movement of the looser material l1.

As best shown in Figs. 2, 3 and 4 each of the sections of jackets l5 and 16 have rolledcorrugations l9 and 20 provided adjacent each of their ends. At each end of the sections of liner ll corrugations l9 and 20 are so located that their centers are spaced somewhat along the longitudinal axis of the sections. corrugations l9 and 20 serve as a means for stifl'ening the sections of the jackets I5 and I6 as well as a means for holding plugs l8 in position; corrugations!!! also serve as expansion distribution stops as will appear hereinafter. Equivalent stiifening elements may be employed in place of corrugations l9 and 20.

The sections of liner I are preferably united by the joint shown in Fig. 2. In effecting this joint a plurality of slotted holes 2| are provided, preferably equallyspaced, around the encircling one of the outer jacket section l5 of the joint jacket sections l5 have a limited independent longitudinal movement, when expanding-or contracting, before they are constrained to move as a unit. The encircled one of the inner'jacket sec-. tions 16 is positioned within the encircling one of inner jacket sections IS with its corrugation 20 spaced from the end. of said ericircling jacket section by a distance about equal to the length of slotted holes 2 I. With this arrangement corrugation 20 of said encircled jacket section and the end of said encircling jacket section act as limit stops for independent movement of their inner jacket sections during expansion of their inner jacket sections it and thus prevent warping and other distortion of said inner jacket sections IS.

The sections of liner N that terminate at flanges 12 have their ends closed as shown in Figs.

gerated in Figs. 1 and 5 so that the construction may be more clearly shown.

Jackets l5 and I6 are formed from sheets that arebent to tube form. The abutting edges of the bent sheets form seams 30, shown in Figs. 1 and 5, which are open to the extent required for maintaining the pressure through the cross-section of pipe In substantially equal. The abutting edges of the bent sheets may be held together at spaced intervals, as by the tack welds shown. The width of seams 30 has been exaggerated for purposes of illustration. Outer jacket I5 is of such a diameter as to fit easily within pipe l0. Inner jacket I6 is of such a diameter that between it and outer jacket l5 may be packed the insulating material I1 and I8 necessary to. secure the desired temperature drop. At present, mineral wool is preferred for insulating material 11 and I8 as this material has the necessary resistance to temperature, is resistant to corrosive media, is of excellent insulating quality and, because of its fibrous character, may be packed to various densities. 0f the mineral wools, lead slag wool, is at present preferred.

At the ends of each of the sections of liner [4 is positioned a plug of insulation [8 of long fiber material; material I! between plugs I8 is preferably in the granular or nodulated form. The

3 or 4. In Fig. 3 the end of inner jacket 16 is bent outwardly to meet the end of outer jacket l5 and united thereto at spaced intervals by tack or spot welds. "The endof inner jacket 18 may be bent as shown in the solid lines or it may be bent as, shown in the dotted lines, in either case cuts are made, equally spaced around the circumference of the end of inner jacket l6, so-that the bending may easily be eifected. In Fig. 4, a separate piece 23 is used to close the section'end. Piece 23 is formed from a tube of appropriate 'length'by bending one end of its outwardly;

again, cuts areprovided equally spaced around the end of the tube so that the bending may be easily effected. Piece 23 is spot or tack welded at spaced points to outer jacket l5 and may be shaped either as shown in the solid lines or as shown in the dotted lines.

It is to be particularly noted that the construction of liner I4 is such that by reason of the open joints of the elements of the sections, the porous character of the insulating material and the perforated ends of the sections, the space between outer jacket [5 and the wall of pipe 10' and the space between inner jacket l6 and outer jacket I5 are in free communication with the space within inner jacket I6 and with each other. Hence, the pressure will always be equal throughout the cross-section of the space within the walls of pipe Hi. It is also to be particularly noted that except at the very ends ,of liner l4 jackets l5 and I6 are unconnected by metal so that throughout liner M the full insulating value of the insulation H and I8 is made use of.

' In Fig. 5 is shown the manner in which the sections of liner M are formed to line the region of pipe in that includes a large connector, such as connecter 25. Liner M in this region is made in three sections 26, 21, and 28.

Section 26 is made in the same manner as the end sections of liner l4 above described and its flange end closed as shown in either Fig. 3 or Fig. 4. The end of section 26 within pipe I is shaped to the contour of the intersecting cylindrical surfaces. This end of section 26 is closed as shown in Fig. 3 except that the outer jacket I is bent to meet the inner jacket 15. In

this case, as before, the bent end is provided with spaced cuts before bending.- Section 21 is formed in the same way as an intermediate section of liner I 4, above described, except for the end below connector 25. This end, above the center of pipe I0 is shaped to the contour of the intersect ing cylindrical surfaces so as to closely match the abutting end of section 26. Below the center line of pipe It the end of section 21 is formed to be in a plane transverse to longitudinal axis of pipe w. The shaped end of section 21 is closed by bending outer jacket l5 to inner jacket I6 as stated in connection with section 26. Section 26 is formed in the same way as the end section of lining Hi, above described, and its inside end formed to match the ends of sections 26 and 21 in the manner described in connection with these sections. Since relative movement between sections 26, 2? and 28 is not desirable these sections are preferably tied together by tack, or spot welds.

While the lining of'a cylindrical body only has' .pipe it), it is a simple matter to calculate from known formulae the thickness of the insulation material, at a. preferred density of pack, required within lining M to give the necessary tem- Perature drop.

While lining I4 is permeable to the extent above stated, it is not permeable to the extent that there is any substantial flow of the material handled, after equilibrium, from-the region adjacent the inner jacket It to the region adiacent the walls of pipe ll. Thus, the heat transfer that takes place by reason of the material handled between the walls of pipe I0 and inner jacket It takes place to a major degree through conduction and radiation between quiescent, or at most slowly moving molecules of the material 'handled rather than by movement or the molecules of the material handled.

Iclaim: 1

1. A tubular insulating member, said member including unconnected concentrically 'disposed inner and outer metal jackets, said jackets being spaced from each other to providean annular ings therein for communication with said annular chamber, and porous insulating material disposed in said chamber to provide a heat barrier between said jackets of substantially uniform heat conductivity, said porous material serving as the sole means for maintaining said jackets in their spaced relation, the insulating material at the ends of said chamber being felt-like and movable as a unit, each ofsaid jackets being corrugated adjacent their ends, said corrugations being disposed in spaced planes transverse .to the longitudinal axis of said member, said corrugations serving to maintain said felt-like insulating material in position.

2. An insulating member including generally concentric inner and outer metal jackets spaced from each other to provide an open ended annular chamber, porous insulating material disposed in said annular chamber, forming a continuous heat barrier of substantiall uniform conductivity, the insulating material adjacent the ends of said jackets being movable as a unit, the remainder of the insulating material being subdivided into individually movable portions, said jackets having at least one passageway therein between their ends providing communication with said chamber for pressure equalization, and means adjacent the ends of each of said jackets serving to stiffen said jackets against collapse and to maintain said insulation movable as a unit fixed in position.

3. In apparatus for handling media at elevated temperatures, a vessel, an insulation liner positioned adjacent the inner surface of the vessel walls, said liner comprising a plurality of sections and means connecting adjacent sections for limited relative movement, each of said sections including spaced inner and outer metal jackets, said jackets providing a'ccntinuous space between them extending for the full length of said liner, porous insulating material in the space between said jackets, the insulating material adja cent the ends of said jackets being movable as a unit, and means at the ends of each of said jackets engaging the insulating material thereat to prevent movement thereof, said jackets including at least one opening therein through which the heated medium can pass for equalizing the pressure within said vessel and the space between said jackets. v

v 4. In apparatus for handling media at elevated temperatures, a vessel, an insulation liner formed of a plurality of sections disposed adjacent the inner surface of the vessel walls, each of said sections including inner and outer metal jackets spaced to provide an uninterrupted annular chamber, porous insulating material filling said annular chamber, the insulating material adjasaid jackets having at least one opening therein open ended chamber. said Jackets having open- II through which the heated medium can pass for equaliZinB the pressure within said vessel and saidchamber, the ends of the Jackets of adjacent sections being 'telescoped within each other with the felt-like insulating material in abutment, and means connecting the telesooped ends of said outer jackets, said means arranged to provide limltedrelative movement between the connected cuter jackets. ALBERT L. BAKER. 

